BIT 1991 Volume 10 Issue 1

Understanding Users' Understanding

A theoretical discussion of mental models is interwoven with conversational
data from an interview study concerned with people's beliefs about the working
of high-street bank machines. The data show that some users do spontaneously
form explanatory models of bank machines, and further allow some insights into
the ways in which models are constructed. The discussion focuses on the
variety inherent in subjects' models; on the spontaneous analogies they invoke;
on the use of cultural, linguistic metaphor and its relation to explanatory
models; and on the observed preference for references to direct empirical
experience.

Fuzzy sets are adequate forms of knowledge representation when the
information is uncertain due to vagueness and imprecision. Knowledge
structures using fuzzy sets are similar to those implemented in non-fuzzy
systems. Classical knowledge elicitation methods can be used in combination
with techniques to develop membership functions. The fuzzy set representation
has several advantages, including flexibility in expressing uncertain knowledge
during elicitation, representation of the knowledge and its uncertainty as a
unique entity, easy interfacing with classical systems, and a more robust
system in ill-defined domains. These advantages result in increased system
reliability.

The paper describes the representation of a complex industrial plant
consisting of a hierarchy of displays of mass and energy flow functions. The
evidence so far available suggests that this representation supports the kind
of reasoning and principles required in fault diagnosis and learning to
understand plant dynamics.

Confidence and Accuracy in Judgements Using Computer Displayed Information

Confidence and accuracy in decision making are often unrelated, contrary to
popular belief. In practice, confidence is often relied upon as evidence of
good decision making, since the quality of a decision is difficult to determine
at the time the decision is made. Information systems are increasingly used to
assist decision making in organizations. Researchers believe that task,
information system, and human characteristics affect the relationship between
accuracy and confidence. In this research, manipulation of task, system, or
human characteristics that led to an increase in confidence in decision making
did not lead to an increase in decision accuracy and vice versa. In this study
decision accuracy was judged by a decision process measure instead of a
decision outcome measure. It was observed that subjects who had higher
numerical skills than spatial skills expressed significantly more confidence in
their decisions in a problem solving task; however, decision accuracy scores
were not significantly better for subjects with higher numerical skills. Thus,
these subjects expressed overconfidence in their decisions. Subjects using
graphical displays (instead of tabular displays) also expressed similar
overconfidence in their decisions. On the other hand, when subjects were given
a less complex task, their decision accuracy scores were significantly better
than subjects who had a more complex task. No significant difference was found
in confidence expressed in their decisions, and therefore subjects performing a
less complex task expressed underconfidence in their decisions. These results
and others in the paper suggest that confidence is a poor surrogate for
accuracy in decision making. Sophisticated software interfaces, like graphical
information displays, could lead to increased confidence in decision making
without significant improvement in the quality of decisions made.

Evaluating Interactive Computer Systems

Successful human factors evaluation of interactive computer systems has
tended to rely heavily on the experience of the practitioner, who has had
little explicit support on which to draw. This paper concerns support for
evaluation in the form of a framework for describing and guiding the general
activity. The paper starts with a critique of current approaches to
evaluation, and particularly of evaluation within the 'design for usability'
approach. Following a definition of evaluation, a framework is proposed that
attempts to clarify what can be done towards which goals and how it can be
done. This highlights and discusses notions of system performance, of
assessment statements, and of assessment methods. The paper concludes with a
discussion of the implications of the framework for evaluation practice.

This study concerns how user training on newly introduced computer
application programs is carried out. Questionnaire data from the computer
managers of 265 Swedish companies were analysed. The results show that formal
training, i.e., teacher-directed group instruction, and self-studies using
instruction manuals represented nearly two-thirds of all reported training
forms. For the most recently introduced program, classes (group instruction)
with simultaneous computer exercises was the form of formal training that was
nearly always used. When formal training was given it was compulsory in over
half of the cases. However, substitutes for users attending a training course
were only provided by the company in very few of these cases. The implications
of these findings for effective user training are discussed.

Organizational Constraints on the Use of Informational Technology

Much concern has been expressed over the last few years regarding the lack
of success of British companies when introducing new technology. Though many
explanations have been given for this, often there is one common factor: the
competence of British managers. This article examines the relationship between
managerial competence and the poor record of British companies in successfully
introducing new technology. It argues that in examining these issues too much
attention is paid to the final decisions taken by the managers, and their
consequences, and not enough to the context -- the organizational circumstances
-- in which the decisions are arrived at. It begins by examining the impact of
organizational structures and practices (socio-structure) on managerial
decision-making. Empirical evidence relating to the purchase of computer
systems is presented which shows how socio-structure limits and shapes
managerial behaviour and success with new technology. It then proceeds to
discuss the relationship between socio-structure and culture, arguing that
these need to be in harmony if organizations are to operate effectively. The
article concludes by positing that many cases of poor decision-making owe more
to inappropriate and conflicting socio-structures and cultures than to the
competence of individual managers.

Research Issues in Object-Oriented Interfaces

The Learnability of HyperCard as an Object-Oriented Programming System

Computer science students are able to learn HyperCard programming in between
to and three days using an incremental learning approach. They have several
problems in understanding the layered object hierarchy in the system.

This study used a standardized evaluation to compare two direct manipulation
graphics interfaces. The interfaces investigated were: (1) object-oriented
(vector) graphics; and (2) bit-mapped graphics (object-oriented graphics
interfaces are not to be confused with object-oriented programming or
object-oriented data bases). Experienced and novice subjects performed
objectively derived benchmark tasks appropriate for two-dimensional graphics
packages.
Both performance and preference data were collected. Task completion time,
aborted attempts, learning effects, and errors constituted the performance
measures. For the preference data, subjects completed questionnaires to rate
the interfaces on both an absolute and a relative basis. Results indicate that
the object-oriented graphics interface is superior to bit-mapped interface for
most tasks included in the benchmark set. The advantages of the
object-oriented interface are especially pronounced for graphic manipulations
such as rotation, resizing (scaling), and general editing.

Self-Describing Animated Icons for Human-Computer Interaction: A Research
Note

Animated icons may offer substantial advantage over static icons for
human-computer communication. Nonetheless, problems and challenges remain.
For example, the constant motion of animated icons can be distracting or
tedious for users. Another challenge relates to the ease of learning and use
of iconic interfaces in general: how can icons provide more helpful information
to users regarding their intended use? In this research note, we describe
animated icons we have implemented which attempt to address these issues.

Case Study -- Assumptions in Electronic Mail Use

Users' comparisons between computer-mediated communication (CMC) and other
forms of communication are of theoretical interest and have important
implications for system design and implementation. This paper outlines the
prevalent systems-rationalist perspective on CMC, which sees the medium
primarily as an efficient channel for information transfer in specific
organizational tasks, and critically reviews the evidence that studies of
users' perceptions and media preferences offer for this generalized view. In
advocating a widening of our perspective on CMC, a field study is described in
which electronic mail users within a large commercial telecommunications
company were invited to compare eight different communication activities, using
repertory grid technique. From a total of 91 user-generated constructs, five
principal dimensions were identified that accounted for users' discrimination
among the different activities. Electronic mailing was construed as being
similar to written activities (such as note-writing) on some dimensions (e.g.,
'asynchrony', 'emotional quality') but similar to spoken, face-to-face
communication on other dimensions such as 'spontaneity'. The results suggest
that the group of users construed CMC mainly in terms of its attributes as a
medium for conversation and social interaction. There was no evidence of
spontaneous task-related media comparisons. These results together with
findings from other studies are discussed in terms of rationalist and symbolic
interactionist perspectives on CMC. Implications for system design are also
considered.

BIT 1991 Volume 10 Issue 3

Experimental Studies in HCI

Early studies of programming and of other more general planning and
problem-solving activities emphasized the hierarchical nature of such tasks.
For instance, the dominant approach to problem-solving and planning views such
processes as top-down focused activities which start from high level goals that
are in turn decomposed into achievable actions via a successive refinement
process. Similarly, empirical studies of the programming activity have
highlighted such top-down and breadth-first decomposition strategies. These
processes are also clearly mirrored in prescriptive accounts of the programming
task. More recent characterizations of the programming activity present an
alternative view -- one which emphasizes the broadly opportunistic nature of
the programming process. From this perspective, program design is seen to
deviate from the top-down, breadth-first model proposed by previous studies.
Here, program design is viewed as opportunistic in the sense that elements of
the design can be created asynchronously at any level of abstraction within the
solution space. Hence, the program design process is seen to be neither
decompositionally nor hierarchically levelled, but mediated by the
serendipitous and opportunistic discovery of new knowledge and design
constraints and so on. The paper presents empirical support for a model of the
program design activity which suggests that the programming process can neither
be viewed as strictly top-down nor as globally opportunistic. Rather, it is
shown that while opportunistic episodes may occur at any point in the evolution
of a program, the programming activity itself is hierarchically structured and
proceeds in a largely top-down fashion. Program design is seen as a
hierarchical goal-directed task with random opportunistic excursions caused
largely by simple cognitive failures.

The paper describes a research study on visual discrimination of textual and
graphic symbols on a visual display terminal (VDT) screen when viewed at
eye-to-screen distances of 61 cm and 152 cm (24 and 60 ins). Conducted as part
of a development programme at McDonnell Douglas Corporation's St. Louis
Aircraft Company for an Integrated Manufacturing Composites Centre (ICC), the
study investigated symbol shapes, symbol sizes, symbol colours and background
colours at the two viewing distances. The longer distance is representative of
required placements of the VDTs at some manufacturing workstations to avoid
interference with process or control equipment. Knowledge gained from the
study was incorporated in the selection of the manufacturing computer
information system (CIS) terminals.
All four treatments showed significant effects on visual discrimination at
both viewing distances and, particularly at the 152 cm distance, the mix of
symbol and background colours was highly significant. A black screen
background colour with more luminous symbols such as orange, green, yellow
provided much better visual discrimination at the extended viewing distance
than less luminous symbols such as red and blue on a white background. Visual
discrimination at the extended viewing distance, when compared with the shorter
viewing distance and using symbols of equal size, was better than the loss in
visual angle would suggest.
Sex and age (to age 65) did not significantly affect visual discrimination
mean scores, but the variance among individuals in the 51-65 years age group
was greater than for the younger age groups.
The visual discrimination scores for symbol sizes of 4 mm² were not
significantly different from the 6 mm² symbols at the 61 cm viewing
distance. The 4 mm² symbol size was therefore adequate for visual
discrimination of standalone symbols at this distance. Although 8 mm symbols
were not use in this study, projections from the data indicate that such symbol
sizes at 152 cm would provide comparable discrimination scores to the 4
mm² at 61 cm.
Improved visual discrimination of standalone symbols occurs with gaps or
changes in the angles of symbols, such as sets 'C' versus 'O' and 'X' versus
'+'.

Surveys of Computer Impact

Reciprocal Effects between Organizational Culture and the Implementation of
an Office Communication System: A Case Study

As part of a study investigating the implementation of an office
communication system and its effects on work and organizational processes in a
large transportation company, reciprocal effects between organizational culture
and the new technology were analysed. It was found that in one department
which was characterized by a well established culture, the communication system
was integrated fairly easily and thereby reinforced the culture. In a second
department, which was in the middle of a strong internal cultural conflict, the
new technology was used unsuccessfully by one subgroup to support cultural
change. By refusing to use the communication system in the intended way, the
other members of the department resisted that attempt. In both departments,
the technology did not effect a change, rather it was integrated into
pre-existing cultural patterns.

The research was inspired by comments from the press and concerned academics
who suggested that computer use could convert 'normal' people into antisocial,
machine-code junkies. Contrary to such opinions, the computer-dependent
individuals who took part in the study were intelligent, interesting,
hospitable, but misunderstood people, who from experience had learned to
mistrust humans. Instead from an early age, they had turned to the safe and
predictable world of the inanimate, and by exploring their environments had
become true scientists and philosophers. Their responses were far from
neurotic, instead they were logical coping strategies which allowed them to
make sense of the world within which they lived. They were pursuing an
interest which not only provided intellectual challenge and excitement in
infinite variety, but for most also enabled them to turn a fascinating hobby
into a successful means of earning a living; an ideal to which most would
aspire.

Models of Computer-Supported Work

The Roles of Computerized Support Systems: A Decision Subprocess-Based
Analysis

This paper analyses the potential roles of computerized systems in
supporting the decision-making process. Toward this end, we propose an
expository process model of decision-making and develop a framework that
provides the infrastructure for the analysis. The proposed process model draws
on two well-known models in the literature and enumerates eight distinct phases
in decision-making. The framework developed is based on an integration of this
process model with Simon's notion of 'decision-structuredness'. Unlike any of
the existing frameworks, the suggested framework permits a micro-level analysis
of support system roles. The analysis is intended as a pre-design guide, to
help systems developers and users to identify support potential and
possibilities, and to target their activities accordingly.

Note: An erratum for this article appears in volume 10, number 6, p. 545

Comment

Comments from the Sidelines: Some Thougths on Research Networks and Network
Research

BIT 1991 Volume 10 Issue 4

Simplifying Complex HCI Issues by Experiment

Past research has demonstrated that reading efficiency is lower from the
standard computer displays of the 1980s than from paper. In the present
experiments, subjects read or skimmed stories, sometimes from a high-quality
CRT (cathode ray tube) and sometimes from a book. Skimming was 41% slower from
the CRTs than from the book. Possible reasons for this finding are discussed.
Reading speed and comprehension were equivalent for the high-quality CRTs and
the book. The paperless office may be imminent after all.

The paper presents a model of how the availability of implementation details
affects performance in designing a human-computer interface. Two experiments
have been used to test the validity of this model. The experiments involved
varying the amount of implementation detail presented to interface designers
and having the designers perform an interface design task. The amount of work
performed and the quality of the resulting human-computer interface design are
analysed.
The results presented in this paper show that the quality of a
human-computer interface design improves if the designer is presented with
information about implementation details. However, presenting a designer with
all implementation details of the system functions results in a lower quality
design. The relevance of these results to human-computer interface design and
future directions for research are discussed.

The study reports results from an experiment investigating aspects of
communicative processes and outcome, using face-to-face, and computer-mediated
communication. Degree of consensus, communication pattern, attitudes to media,
and personality (extroversion-introversion) were studied. The subjects
operated computer-mediated systems as a daily work-tool. There were two
different problems to be discussed; a human relations problem and a problem
involving judgement of important equipment for survival after an
airplane-crash. The results showed no differences in problem-solving
efficiency due to medium used, but difficulties to reach consensus in the
inexperienced groups. There were no main effects of medium on equality and
dominance, but several significant results in the survival problem, showing
that face-to-face communication induces more conformity and opinion change as
compared to computer-mediated communication. Face-to-face communication was
preferred and there were only weak relationships between personality and other
variables studied.

The Impact of Interface Customization on the Effect of Cognitive Style on
Information System Success

The paper investigates the impact that customizing the user interface has on
the effect that the users' cognitive styles have on the success of an
information system. The study was carried out on an office automation (OA)
system, which was implemented in an institution of higher learning to support
the top administrators in their work. Pearson and Bailey's user formation
satisfaction (UIS) instrument was used to measure the success of the system,
while the Myers-Briggs Type Indicator (MBTI) was used to determine the
cognitive style of the user. The results provided evidence that support the
proposition that by customizing the interface to suit the idiosyncrasies of the
user, the effect that the cognitive style of the user has on the success of the
OA system can be reduced, if not removed. This result suggests that if the
interface to OA system can be customized, then system designers do not need to
consider the users' cognitive styles explicitly when they are designing the
system.

Developing Promising HCI Research Approaches

Language, Communication, Social Interaction and the Design of Human-Computer
Interfaces

The importance of human sciences to the design of information technology is
now generally recognized. As part of this recognition there is an interest in
employing findings about language, communication and social interaction in
design. In particular there has been a great deal of recent interest in the
use of the methods and findings of conversation analysis, a sociological
approach to the investigation of the structure of human conversation. The
paper discusses the rationale for the use of such findings, outlines directions
currently being pursued in this area, and provides a bibliography of
recently-published and forthcoming research.

Measurement of Stress to Gauge User Satisfaction with Features of the
Computer Interface

Human stress in a computer-related job situation can result from a variety
of causes. A comprehensive cause-and-effect model is developed, using
extensive confirmation from the literature. Then, the components of user
satisfaction are defined and a conceptual measure of user satisfaction is
constructed. These definitions use the same cause-and-effect relationships
that were identified for user stress. Based on the conjecture that stress, or
lack thereof, is an appropriate indicator of the user's level of
(dis)satisfaction with a system, a measurement methodology is proposed. It is
intended to determine both how satisfied a user is with an interface and what
the causes of (dis)satisfaction might be. Techniques for obtaining objective
indicators of the user's stress levels are surveyed. A general experimental
procedure is outlined and its verification is described. The methodology is
considered to be particularly important for application to critical,
high-pressure jobs, such as those in air traffic control and in the nuclear and
chemical industries.

BIT 1991 Volume 10 Issue 5

Methodological Issues

Although usability testing may be a well accepted and widely practised
component of the commercial software development process, improper application
of testing techniques may lead to poorly designed software. The present paper
discusses a number of potential problems which designers may face in the
process of conducting usability tests on their products. These problems may
include difficulties in sampling, methodological problems in planning and
conducting tests, validity and reliability of obtained measures, and
misinterpretation of results. A number of suggestions to avoid or lessen the
impact of these problems are also discussed.

Three Approaches to the Input of Human Factors in IT Systems Design: DIADEM,
The HUFIT Toolset and the MOD/DTI Human Factors Guidelines

Parameters for defining the applicability of a human factors input to IT
systems design are outlined first. The paper then compares and contrasts three
methodological approaches developed at the HUSAT Research Institute. Each
approach is detailed in terms of its developmental domain, content,
applicability and availability. Commonalities in the three approaches are then
investigated and an outline of the uptake of each approach is given. In
conclusion, summary advice is offered on selection criteria for the three
techniques.

The Role of Knowledge in Human Computer Systems

Feedback as a Source of Control in Decision Support Systems: An Experiment
with the Feedback Specificity

Well-designed feedback can improve decision-making, but to date, there has
been no comprehensive study of feedback in decision support systems that could
guide developers in its design. This work examines the opportunities and means
to enhance the user's consistency in implementing a decision strategy (a plan
for making the decision) by providing appropriate feedback. It concentrates on
the specificity of feedback. Feedback is said to be specific if it provides
details about the decision-making process that help correct the process;
feedback is non-specific if it merely reports outcome without indicating what
caused it. The paper builds on concepts from cognitive engineering,
behavioural decision-making, and systems design to examine how
computer-generated feedback enhances the user's decision consistency, and
reports on a laboratory experiment. Specific feedback found to be effective in
enhancing decision consistency, but its impact is compromised by the presence
of additional non-specific feedback.

If effective knowledge-based support is to be provided for software
designers, the process of software design, and the classes of knowledge used by
designers must be understood more clearly. It has been shown that software
designer's experience of designing software in the current application domain
has a significant effect on the production of a quality design. However, in
gaining experience of designing software, a designer gains knowledge in various
distinct areas, including software design and the application domain. It is
currently unclear which elements of this experience are important. In
particular, the role of application domain knowledge that is independent of
software design is of great significance for builders of intelligent software
design support systems, since the overheads involved in providing application
domain knowledge for a variety of application domains in such systems would be
huge. This paper reports on a study that has been carried out to gain insights
into this question, based around the structured techniques of DeMarco (1979)
and Yourdon and Constantine (1979). From this preliminary investigation it
would appear that a designer's general knowledge of the application domain does
not affect the quality of a design produced for a system in this domain; this
runs contrary to current popular beliefs.

A model of a human neural knowledge processing system is presented that
suggests the following. First, an entity in the outside world tends to be
locally encoded in neural networks so that the conceptual information structure
is mirrored in its physical implementation. Second, the knowledge of problem
solving is implemented in a quite implicit way in the internal structure of the
neural network (a functional group of associated hidden neurons and their
connections to entity neurons) not in individual neurons or connections.
Third, the knowledge system is organized and implemented in a modular fashion
in neural networks according to the local specialization of problem solving
where a module of neural network implements an inter-related group of knowledge
such as a schema, and different modules have similar processing mechanisms, but
differ in their input and output patterns. A neural network module can be
tuned just as a schema structure can be adapted for changing environments.
Three experiment were conducted to try to validate the suggested cognitive
engineering based knowledge structure in neural networks through computer
simulation. The experiments, which were based on a task of modulo arithmetic,
provided some insights into the plausibility of the suggested model of a
knowledge processing system.

The research lays the groundwork work or a taxonomy of visual
representations by establishing a methodology for determining the kinds of
knowledge conveyed by different graphical representations. In the first of two
experiments, the basic categories and dimensions of a set of graphics were
established using a sorting procedure. Five principal categories emerged:
graphs/tables, maps, diagrams, networks, and icons. Furthermore, two principal
dimensions characterize these groups: amount of spatial information and amount
of cognitive processing effort. The second experiment validated and extended
this understanding of the cognitive structure of visual representation. In
that experiment, similarity among items was assessed using pairwise similarity
judgments. The results confirmed the original categories and revealed distinct
differences between subjects who did or did not have graphic arts training.

Classifying Users

There are many research reports directed at establishing the characteristics
and needs of new or inexperienced computer users, and indeed these have been
the topic of at least three substantial review articles in the last decade.
Most of these studies, however, make little effort to report carefully the
defining characteristics of their samples beyond the use of intuitive and
tautologous labels such as 'expert' or 'naive' and so on. Inevitably this
leads to difficulties in interpretation and generalization of findings. The
paper outlines some conceptual considerations in separating out terms applied
to computer user samples and suggests a basis for a fuller reporting of sample
parameters which would aid comparison between reported studies.

BIT 1991 Volume 10 Issue 6

HCI Myth 1 -- 'A Picture is Worth One Thousand Words'

This paper presents a methodology and results of an experiment to assess the
usability of menu items constructed of text, icons, and text-and-icons.
Attributes of menu items are used to form a matrix which can be used to
classify menu items for use in certain applications, tasks, or with users of
particular experience levels. An experiment was conducted to validate a
portion of the attribute matrix. Performance measures were accuracy of
selection and time to make a selection. Results suggest that menus constructed
of a mixed format (text and icons) result in the fewest number of incorrect
selections by users. No significant differences in the time to make a
selection were found.

Graphing in Depth: Perspectives on the Use of Three-Dimensional Graphs to
Represent Lower-Dimensional Data

Embellishing simple graphs by adding perspective, 'the 3D look' has become
increasingly commonplace with the ready availability of graphics software.
However, the effect of adding such decorative depth on the comprehension and
recall of the graph's message has received little attention. The present study
evaluated performance on such common graphical formats as line graphs, bar
charts and pie charts constructed with and without the 3D look. When subjects
were asked to make relative magnitude estimations, only the 3D line graphs
resulted in reliable performance decrements. Likewise, information presented
in 3D line graphs was remembered less accurately than information presented in
2D line graphs. For the estimation of global trends, both 3D line graphs and
bar charts were used more quickly than 2D formats, but this speed was obtained
at the expense of accuracy. For a trend classification task involving more
focused processing, 3D line graphs and bar charts were associated with an
overall performance decrement when compared with their 2D counterparts.
Finally, the use of 3D designs, in addition to modifying performance, may
influence the attitudes formed by subjects toward the information presented in
the graphs.

HCI Myth 2 -- 'Everyone Knows How to Use a Spreadsheet'

Measuring the Learnability of Spreadsheets in Inexperienced Users and Those
with Previous Spreadsheet Experience

The issues of 'usability' and 'learnability' are assuming an increasingly
important role for both the designers of software and their prospective
customers. Objective measures of the interaction between system and user are
important for the development of software that is both easy to learn and
pleasurable to use. In this study, we apply a set of five measures to evaluate
users' interactions with spreadsheet software, and to compare two spreadsheet
packages. We tested 16 people with no previous experience of spreadsheets and
16 with experience of spreadsheets generally though not of the spreadsheet we
gave them. Half were allocated to learn Excel and half to learn Wingz, running
on Apple Macintosh computers. A standard task was constructed to assess
understanding of the basic concepts involved in the use of spreadsheets.
Users' previous experience of spreadsheet use was the most salient factor in
the scores achieved on the task. The brand of spreadsheet had no significant
effect on task performance. Implications for designers of software and users
of spreadsheet packages are discussed.

The increasing need to instruct students in the use of personal computer
software, especially electronics spreadsheets, is placing greater demands on
the already full university curriculum. A potential help in meeting these
demands is the readily available computer-based software tutorials. In order
to explore the feasibility of computer-based instruction as an alternative to
human instruction, this research compares two modes of instruction,
computer-based and human. An experiment was conducted with groups of business
student subjects. The research results indicate no difference in students'
attitude towards computer-based instruction and human instruction of
spreadsheets. Students' short-term recall of the software syntax being taught
is as strong with computer-based instruction as with human instruction. These
results were not affected by the level of personal computer experience that
students had prior to the experiment. However, the ability to comprehend and
immediately apply the software to a task is greater with human instruction than
with computer-aided instruction. This advantage holds true for students
instructed by experienced and inexperienced instructors.

HCI Myth 3 -- 'Office Automation'

We investigated a recently introduced office automation system at Swedish
Telecom. In a first study, where 275 users answered an inventory, the users
indicated that they found the system useful, but that they would like better
user support. Paper and on-line support were most often used at the syntax
level, but were not regarded to be very satisfactory. Human advisors were
found to be consulted most often, as well as being reported the most
satisfactory means of support at the task and conceptual levels. In an
interview study concerning the electronic mail system, the results from 35
users showed that the users were satisfied with the system, but that they knew
fairly little about it, particularly at the semantic level. A third study
showed that the system support personnel knew their users rather well. When
asked to describe the system, system support personnel mainly described the
system in computer terms, whereas many other users described it
non-informatively. It is concluded that knowledgeable human advisors are
needed to support the efficient use of a system by illuminating task and
semantic aspects. At the same time, easy-to-use manuals are needed to support
the reminding about syntactic and interaction details.

HCI Myth 4 -- 'There's Nothing More to Say about VDUs'

Vision is the result of complex neural computation. It is argued that
cathode ray tube displays make the neural computation more complex than it
needs to be because (1) they pulsate in brightness; (2) they present a visual
image which is spatially periodic but which demands precise control of eye
movement; and (3) the spectral power distribution of light emitted by the
phosphor is uneven.

Linear regression is often used to analyse and summarize data, and to
uncover, clarify, and simplify a data structure. The outcome of these
activities depends of both the analyst's domain-specific knowledge and on the
data. Analysing the data also affects the analyst's understanding about the
data and, hence, the act of analysing data is inherently a recursive activity,
with each new iteration potentially providing additional insights. This
process calls for a strategy of exploratory data analysis that consists of
techniques for flexibly analysing, summarizing, and re-expressing the data.